Rel is the one sub everyone compares their product to especially on this site.Just about every post on this site when talking subwoofers references Rel
The above statement is not necessarily true...Definitely not just about every post about subs...
REL is way over priced for what you get.
There’s also GR open baffle subwoofers not mentioned in this post.
Take a look at Power Sound Audio, and as mention earlier Rythmik, very musical subs for the money with phase and other adjustments with Rythmik having multiple connection options to be considered also.
@audiokinesis, there’s something to be said about a subwoofer manufacture that gives advice on how to maximize a competitors subwoofer’s musicality and output with nothing but positive and constructive things to say and more importantly what to do to get there.
OP, I admire you taking on using REW also for better subwoofer output and pleasing sound.